Young adults, age 20-35, experience the greatest rate of weight gain, averaging 1 to 2 pounds per year. This weight gain is associated with a worsening in cardiovascular risk factors and an increase in the prevalence of metabolic syndrome. Given the difficulties in producing sustained weight loss later in life, preventing weight gain from occurring during young adulthood is critical to curbing the obesity epidemic. This project involves two linked R01 applications--a Clinical Coordinating Center application submitted by Dr. Rena Wing, The Miriam Hospital, and a Data Coordinating Center, submitted by Dr. Mark Espeland, Wake Forest University School of Medicine. The purpose of the project is to test two interventions to prevent weight gain in young adults. Both interventions are based on a self-regulation approach that we have shown can help prevent weight regain in recent weight losers. Key aspects of this self-regulation include daily self-weighing, use of the information from the scale to know when adjustments in eating and activity are needed, behavioral skills to modify these behaviors, and small reinforcements for successful prevention of weight gain. One self-regulation intervention is focused on making small consistent changes in eating and exercise behavior to prevent weight gain;the other emphasizes periodic larger changes in eating and exercise behavior that result in small weight losses. These interventions will be compared to each other and to a control condition in a 3-armed randomized controlled clinical trial. The study will involve 600 adults (300 at the Miriam Hospital clinical site and 300 at the University of North Carolina clinical site), aged 18-35 with a BMI of 23-30, who are randomly assigned to 1) control;2) self-regulation intervention with small behavior changes or 3) self-regulation with large behavior changes. Participants will be recruited over 18 months and will be followed from randomization until the end of the grant, resulting in 24-48 months of follow-up (mean=3 years). The primary hypothesis is that the magnitude of weight gain across an average planned follow-up of 3 years will differ among the three groups (a priori hypothesis is that weight gain will be greatest in control, intermediate in small changes, and least in the large change condition). Secondary hypotheses will compare the three groups on the proportion gaining weight (defined as >1lb over baseline), changes in cardiovascular risk factors, and changes in the process measures (such as diet, physical activity, and dietary restraint). This project focuses on weight gain in young adults-a critical time for the prevention of obesity-and tests innovative approaches based on self-regulation of body eight. This approach shows promise for reducing weight gain and thereby improving long-term cardiovascular health. (End of Abstract)